Signatures of 16 pages, and 4 page increments, conventionally are prepared from preprinted webs having four rows of equal width of areas of printed material corresponding to separate pages of the magazine. The lateral edges of the web are extended beyond the outer edges of the outermost or side rows for a distance of from about 5/16" to about 3/8" in order to form a bindery lap or lip, sometimes called a lap margin, along one edge of each sheet which makes up a signature after the web has been folded to make the same. The bindery laps are necessary and used for opening the signatures for inserting them, one within another, in the binding process, although such laps are cut off subsequently in the final trimming operation on the magazine. The cutting off of such laps in the trimming operation results in a wastage of paper.
One type of 16 page signature is made from two preprinted webs which are slit into two ribbons of equal width. The four ribbons are then superposed with proper collation and folded about a longitudinal fold line, offset from the center line of the ribbon so that the extended margin along one side of each ribbon will form the bindery lap of the resulting signature. The signatures are formed by laterally severing or cutting the superposed ribbons, either before or after the folding operation, into segments of a size slightly larger than a page of the magazine.
Another type of 16 page signature, called a catalog or chopper signature, is made from a single preprinted web which is first folded about a longitudinal center line and then laterally severed or cut either before or after the first folding operation into segments of a length slightly greater than twice the height of a page of the magazine. Each segment is then folded again about its lateral center line, and then again about a fold line offset from the longitudinal center line of the twice folded segment so that the extended margins of the web will form a bindery lap along one edge of each sheet making up the final signature. After the signatures are assembled the final trimming operation removes the first and second connecting folds, as well as the bindery laps.
In both types of signatures, however, there is a considerable wastage of paper in providing bindery laps along one edge of all the sheets making up the signatures, which laps are ultimately trimmed off.